The present invention relates to a compound needle comprising a needle body and a slider to be placed on a needle bed of a knitting machine. More particularly, the present invention relates to a compound needle of the type where tongues of a slider are composed of two superposed blades.
A compound needle is known which comprises a needle body having a hook at a front end thereof and a slider and is so structured that the needle body and the slider can move relative to each other to open and close the hook. The applicant of this application previously proposed this type of compound needle in Japanese Patent Application No. Hei 10-109675 in the title of the invention of xe2x80x9cCompound Needle of Flat Knitting Machinexe2x80x9d.
In the known compound needle, two blades of the slider are accommodated in a superposed state in a blade groove formed in the needle body. The blades are formed to have a thickness smaller than the width of the groove so as to define gaps between the blades and side walls of the groove so that they are supported in the groove in such a manner as to be freely movable forward and backward therealong. This may cause the blades to be unstably positioned with respect to the widthwise direction of the blade groove to only the extent corresponding to the gaps.
This raises a difficulty in centering the blades in the blade groove. This problem becomes prominent particularly when a stitch loop is rested on the tongues at the front ends of the blades that are under large lateral tension to the stitch loop from the knitting fabric.
When the blades are under unstable centering and are out of position in a lateral direction from the center of the groove, the problem may arise that when the slider moves forward, the blades may collide with or pass along one side of the hook without being forked by an end of the hook, to hinder the proper action that the tongues are forked at the front ends thereof by abutment with the end of the hook, so as to hold the hook in sandwich relation from both sides thereof and close it. This may create possible drawbacks in the durability of the needle and the knitting operation.
Even when the blades are forked by the end of the hook and properly actuated, the forked blades are each extended straight in an oblique direction along the sides of the hook at a loop transferring position into which the blades are further moved forward beyond the hook. As a result of this, the forked blades are expanded to the right and left at the front end portion thereof in a sector form when viewed from the top. This may create the following problem when the compound needles thus designed are used with a flat knitting machine having a pair of spaced apart, front and back needle beds on which knitting members such as sinkers and loop pressers are positioned in the vicinity of the compound needles and are moved forward and backward with respect to a needle gap between the needle beds. When transferring the loops, the blades come close to the knitting members to occlude the space for the loops resting on the tongues to be transferred to receiving needles, and as a result of this, there a drawback may arise during the knitting operation.
The objective of the present invention is to make centering the blades of the compound needle in the blade groove formed in the needle body more reliable. In addition, the objective of the present invention is to suppress outward expansion of the front end portions of the blades when guided to the loop transferring position beyond the hook.
According to the present invention a compound needle comprises a needle body having a hook at a front end thereof and a slider having tongues formed by two superposed blades. The needle body and the slider can be freely moved forward and backward individually in the state in which the blades of the slider are supported in a blade groove formed in the needle body. A centering means brings side surfaces of the blades in the blade groove into press-contact with side walls of the blade groove of the needle body so that front end portions of the blades can be held in positions that are equally divided to the right and left from a widthwise center of the groove with respect to a widthwise direction of the groove (hereinafter it is referred to as xe2x80x9ccenteringxe2x80x9d.
The centering means is preferably formed by bends provided in the blades.
The bends are preferably formed so as to be away from each other so that when the blades are exposed from the blade groove and are advanced toward the hook, the blades can open their mouth at the front ends thereof.
Preferably, the compound needle is formed as a transferring needle that is designed so that the front ends of the blades of the slider are advanced further beyond the hook to transfer a stitch loop at the advanced position, and the bends are configured so as to narrow the space between the front ends of the blades when the front ends of the blades are advanced to the loop transferring position beyond the hook.
The bends are preferably formed in portions of the blades in which the blades are completely exposed from the blade accommodating groove in the loop transferring position.
Preferably, the compound needle is formed as a transferring needle that is designed so that the front ends of the blades of the slider are advanced beyond the hook to transfer a stitch loop at the advanced position, and the bends are configured so as to be oriented in a direction for them to be pressed to each other so as to narrow the space between the front ends of the blades when the front ends of the two superposed blades are advanced to the loop transferring position beyond the hook.
The centering means is preferably formed as something to bring either upper edges or lower edges of the blades into press-contact with side walls of the blade groove.
The centering means is preferably formed by twists provided in the blades.
According to this invention, in the compound needle comprising the needle body and the slider, the blade parts of the slider are accommodated and supported in the blade groove formed in the needle body. Each blade of the slider is provided with the centering means, and each blade is provided with a bend serving as the centering means formed in a portion thereof that goes in and out from the blade groove. The bends of the blades can bring the side walls of the blades into press-contact with the side walls of the groove so as to correct the out-of-position of the blades to the right or left in the groove resulting from the gaps defined between the blade groove and the blades so as to always place the blades in the center of the groove.
According to this invention, when the slider is moved relative to the needle body in a direction for the hook to be closed by the slider, the blades are centered in the groove. When the front ends of the tongues are abutted with the front end of the hook, the blades can be forked at the front ends thereof to hold the hook in sandwich relation from both sides thereof to reliably close it.
The centering means is configured so as to bring either of the upper edges and the lower edges of the blades into press-contact with the side walls of the blade groove, and as such can allow the gaps between the blades and the side walls of the blade groove to be filled in so as to center the blades. The tongues at the front ends of the blades are expanded by the action of the twists, and as such can allow the blades to be further reliably forked by the hook.
In the case where the compound needle is formed as a transferring needle that is designed so that the front ends of the blades of the slider can be advanced further beyond the hook, since the bends are configured so as to suppress expansion of the space between the front ends of the blades when the front ends of the blades are advanced to the loop transferring position beyond the hook, even when the knitting members, such as sinkers and loop pressers, are positioned in the vicinity of the compound needles, the knitting problem caused by the blades coming close to the knitting members can be prevented. This can be achieved by the bends of the blades being configured so as to be oriented in a direction for them to be pressed either toward or away from each other.